Quick answers
- Is CVE-2026-58264 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-58264 being exploited in the wild.
- How severe is CVE-2026-58264?
- Critical severity, with a CVSS score of 9.8, published 18 September 2026.
- Which products and versions are affected?
- FluidSynth 1.1.2 to 2.5.5.
- Is there a fix for CVE-2026-58264?
- A patch was published on 2026: Fixed in version 2.5.6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-58264 attacked?
- It is attacked over the network or with local access.
- Am I affected by CVE-2026-58264?
- Check whether you run FluidSynth at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The pitch_bend_range command handler accepts a channel argument that is not bounds-checked before being used as an array index to write to the synth's channel array, resulting in an out-of-bounds heap write. The vulnerability is reachable remotely when the TCP server is enabled via new_fluid_server() or the -s flag, and locally through malicious input to the shell interface. A bounds check added in version 2.5.6 mitigates the issue.
Affected products
- FluidSynth FluidSynth 1.1.2 to 2.5.5
Timeline
- 2026-09-18: disclosed
- 2026: patched: Fixed in version 2.5.6